One potential issue I see is that the ruined keep looks a little too similar to the ruined castle - the basic versions are distinguished by the tower height, whereas your ruined versions have more similar heights.

Orcs seem to like burning stuff, so I think the wooden parts would be burnt. An idea for the keep - have the castle look as if all the timber was ripped out and thrown on to a bonfire on the middle hex, with the large charred area being the keep itself.

One potential issue I see is that the ruined keep looks a little too similar to the ruined castle

i tried not to completly demlish the entire castle. i was afraid that it will not be recognizable in the end.
for better understanding i post some of the conections too since the base image show only 1 of the 6 sides of the hexagon.

I am sure they do, but why would they burn their own keep/castle. Rivalry maybe. Loyalist would might use fire while sieging as well.
Burned wood sounds interesting, maybe some darker spots/spikes on the wood. But if add much more embellishment, it could take too much attraction and totally defocus from everything else. Orcich Castle is full of clutter already, while destruction, that clutter cannot simply disappear.

I post a list with all connections needed for this to work as intended.

I did not understand why the solid cornerstones crumble while the vulnerabler wooden palisade stays more or less the same. The walls would have suffered the bulk of the damage, because now it looks worn down and damaged, yet still intact, inspecially the keep tile.
Still, in the light of having no other ruined orcish castle we could use them, maybe.

why the solid cornerstones crumble while the vulnerabler wooden palisade stays more or less the same.

more destroyed wood --> more embellishment --> more clutter, i tried to avoid that much clutter

Maybe just remove some of it? If it needs a justification, in Wesnoth it seems that armies often need to set up encampments quickly; so maybe the orcs take the best logs from the palisade with them for building the next encampment.

Well done! That indeed looks a lot more ruined, you can proceed with the remaining walls.
For how to implement, look into BfWdir\data\core\terrain-graphics.cfg If that remains too much chinese, you can attach the set on this thread after completing the set, one of us will deliver an screenshot on how it looks ingame.

You can pretty easily test these in-game yourself; in the aforementioned terrain-graphics.cfg, there's 3 NEW:CASTLEWALL* lines for the current castle/orcish/ images. Just change those paths to point to your images instead, and there you go. Then if you want, you can easily take comparison screenshots by just drawing some orcish forts in the editor, switching the paths to your new version and pressing F5 to reload everything.